1. Field of the Invention
The present invention relates to a barrier device for opening and closing a front surface of an optical lens of optical equipment to protect the optical lens not in use, and relates to an image pickup apparatus having the barrier device.
2. Description of the Related Art
Conventionally, a barrier device for covering a front surface of an optical lens of optical equipment to protect the optical lens has been known and widely used for image pickup apparatuses such as a camera having a motor-driven retractable barrel.
Japanese Laid-open Utility Model Publication No. H3-18519 discloses an image pickup apparatus including a barrier device having barrier blades that are opened and closed to prevent a surface of an optical lens from being adhered with dust and stain and from being scratched (hereinafter, referred to as the first conventional barrier device). FIGS. 14 and 15 respectively show a fully closed state and a fully open state of the barrier blades of the first conventional barrier device. This barrier device includes a pair of barrier blades 202, 203 for openably covering a light incident opening 208a of a lens barrel 201.
With the progress of downsizing of image pickup apparatuses, lens barrels are demanded to be compact. However, if the lens barrel 201 of the first conventional barrier device is made small, there is a fear that outer peripheral portions 202a, 203a of the barrier blades 202, 203 extend beyond the lens barrel 201 when the barrier blades are fully opened, resulting in a poor appearance.
In this regard, a barrier device has been known in which the area of each barrier blade is reduced while increasing the number of barrier blades and disposing the blades so as to overlap one another in an optical axis direction, as disclosed in Japanese Laid-open Patent Publication No. 2007-102086 (hereinafter, referred to as the second conventional barrier device). In this barrier device, a retraction space for the barrier blades in the fully open state is made small, thereby realizing a reduction in lens barrel diameter. FIGS. 16 and 17 show the barrier blades of the second conventional barrier device in perspective view and in front view. This barrier device uses metallic barrier blades that can be formed to be thin, thereby suppressing the increase in blade thickness in the optical axis direction.
More specifically, the barrier device has barrier blade pairs 301, 302, and 303. The barrier blades 301 are formed with bent portions 301a bent in the optical axis direction, and the barrier blades 303 are formed with similar bent portions 303a. When the barrier blade pairs 301 to 303 move in the closing direction, the bent portions 301a of the barrier blades 301 drive the barrier blades 302, so that the barrier blades 302 move with a movement of the barrier blades 301. On the other hand, when the barrier blade pairs 301 to 303 move in the opening direction, the barrier blades 302 drive the bent portions 303a of the barrier blades 303, so that the barrier blades 303 move with a movement of the barrier blades 302.
Since the barrier device is generally provided at a tip end of the lens barrel, the barrier device is likely to suffer from large impact due to fall accident and likely to be applied with an external force provided by, e.g., a user by touching the barrier device. When applied with a large external force, there is a fear that the barrier blades are displaced relative to one another in the optical axis direction, resulting in gaps between the barrier blades being broadened.
In the second conventional barrier device, there is a case where the barrier blades 301, 302 are relatively displaced in the optical axis direction by an external force, so that gaps between the barrier blades are broadened. In that case, amounts of engagement of the bent portions 301a of the barrier blades 301 with the barrier blades 302 decrease. Thus, there is a fear that the bent portions 301a fail to properly drive the barrier blades 302, and the barrier blades 302 do not move with a movement of the barrier blades 301.
Also, there is a case where the barrier blades 301, 302 are largely displaced relative to each other in the optical axis direction by an external force, so that the bent portions 301a of the barrier blades 301 run on the barrier blades 302. In that case, the barrier blades 301 cannot return to a normal position, even if the external force is removed, resulting in an operation failure.
The above-described phenomena can also occur between the barrier blade 302 and the bent portion 303a of the barrier blade 303.